Method for producing isocyanate

A technology of isocyanate and crude isocyanate, which is applied in the field of isocyanate production, can solve the problems of not describing the purity of circulating solvents, etc.

Active Publication Date: 2008-11-12
COVESTRO DEUTSCHLAND AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Also, the required purity of the recycled solvent is not described in this document

Method used

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  • Method for producing isocyanate
  • Method for producing isocyanate
  • Method for producing isocyanate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Example 1 (Preparation of a mixture of diamine and polyamine)

[0035] In a stirred container, 2600 grams of aniline and 1000 grams of formalin (based on the weight of the solution, 30% by weight aqueous formaldehyde solution) are thoroughly mixed under stirring and at 25°C, during which time the mixture is heated To 60°C. Turn off the stirrer, and separate and remove the water phase stabilized on the upper part. Then, 68 g of a 30% by weight hydrochloric acid aqueous solution was mixed in, while stirring and cooling, and the temperature was maintained at 45°C. Stirring was continued at this temperature for 15 minutes, and heating was used instead of cooling. The mixture was uniformly heated to 140°C under a pressure of 5 bar within 120 minutes, and maintained at this temperature for 15 minutes.

[0036] Then, the mixture was cooled to 100°C, reduced to normal pressure, and 54 g of a 50% by weight aqueous sodium hydroxide solution was added for neutralization while stirri...

Embodiment 2

[0042] Example 2 (Use contaminated solvent to produce a mixture of diisocyanate and polyisocyanate (not according to the invention))

[0043] In a stirred reactor, the mixture of 1900 g of diamine and polyamine obtained in Example 1 was dissolved in 5700 g of chlorobenzene. The phosgene content was 200 ppm based on the weight of the solvent chlorobenzene. MDI The content is 200ppm. In a second container made of stainless steel (DIN 1.4571), a 33% by weight (based on the weight of the solution) phosgene solution was prepared by dissolving 3800 grams of phosgene in 7600 grams of chlorobenzene, while cooling to At 0°C, mix the amine with the phosgene solution while stirring vigorously. The resulting solid suspension is then slowly heated to form hydrogen chloride gas, which is collected by a suitable device. During this process, a homogeneous polyisocyanate solution is formed. The solvent was separated and removed by distillation, and as a result, a mixture of 2370 grams of diisocy...

Embodiment 3

[0051] Example 3 (Use pure solvent to produce a mixture of diisocyanate and polyisocyanate (according to the present invention))

[0052] In a stirred reactor, the mixture of 1900 g of diamine and polyamine obtained in Example 1 was dissolved in 5700 g of chlorobenzene. Based on the weight of the solvent chlorobenzene, the phosgene content was 20 ppm, and MDI The content is 20 ppm. In a second container made of stainless steel (DIN 1.4571), a 33% by weight (based on the weight of the solution) phosgene solution was prepared by dissolving 3800 grams of phosgene in 7600 grams of chlorobenzene, while cooling to At 0°C, while stirring vigorously, mix the amine with the phosgene solution. The resulting solid suspension is then slowly heated to form hydrogen chloride gas, which is collected by a suitable device. During this process, a homogeneous polyisocyanate solution is formed. The solvent was removed by distillation, and as a result, a mixture of 2370 grams of diisocyanate and poly...

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Abstract

Isocyanates, preferably diisocyanates and polyisocyanates of the diphenylmethane series (MDI), are produced by reaction of amines dissolved in a solvent with phosgene in the same solvent to form the corresponding isocyanates. Hydrogen chloride and excess phosgene are subsequently removed from the reaction mixture to obtain a crude isocyanate-containing solution. Subsequently, the crude isocyanate-containing solution is separated by distillation into isocyanates and solvent. The solvent is recycled and used for the production of solutions of the amines and of phosgene. The solvent being recycled is treated to reduce the phosgene and diisocyanate contents before being used for the production of the solution of the amine.

Description

Technical field [0001] The present invention relates to a method for producing isocyanates (preferably diisocyanates and polyisocyanates (MDI) of the diphenylmethane series). The method comprises reacting amines dissolved in a solvent with phosgene to form the corresponding isocyanates, and then removing Hydrogen chloride and excess phosgene, then the crude isocyanate-containing solution obtained in this way is separated into isocyanate and solvent by distillation, and the solvent is recycled to produce a solution of amine and phosgene, wherein the solvent part used to produce the amine solution contains a small amount Phosgene and diisocyanate. Background technique [0002] The production of isocyanates by reacting primary amines with phosgene is a well-understood prior art. A solution of an amine in a suitable solvent is usually reacted with a solution of phosgene in the same solvent. For example, the production of organic isocyanates from primary amines and phosgene is describ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C263/10C07C265/14
CPCC07C263/10C07C265/14C07C263/18
Inventor B·凯基恩霍夫H·路库姆M·伯姆
Owner COVESTRO DEUTSCHLAND AG
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